The invention relates to writing instruments, specifically pens and pencils having unique and distinctive characteristics, features and feel. In particular, the invention provides such writing instruments having very highly detailed, preferably pewter metal castings thereon, and a process for the manufacture of same.
Writing instruments have existed at least from prehistoric times, viz. the crude symbols and pictures found on the walls of ancient caves. Over the years, writing instruments have been perfected and evolved to the present day, wherein pens and pencils are available in a wide variety of shapes and sizes, and range in cost from a few cents to hundreds of dollars. Individualized pens and pencils today are the products of a large and worldwide market. Pens and pencils which are embellished with the owner's initials engraved in gold or silver form prized keepsakes indeed, and become possessions which last a lifetime in some instances.
Ball point pens can be found in both the retractable type, in which the writing tip extends from and retracts into a barrel, for example by pressing on a push button at the distal end of the barrel or by rotating one portion of the barrel relative to another portion. Such pens are also available of the fixed type, some having removable caps, in which the writing tip at the proximal end of the barrel is permanently affixed to the barrel. Generally the retractable types are more costly to manufacture and, as a result, are more expensive than the fixed type. The retractable types are preferred for their ease of transport in a pocket or purse, because the writing tip can be retracted and will thus not mar or stain a shirt pocket or purse or objects therein.
For convenience and clarity of description, the present discussion and specification will focus upon the retractable type of ball point pen. However, the principles described, and the claims appended hereto, are all-encompassing and apply to fixed tip pens, of the ball point and/or the liquid ink variety, as well as to mechanical pencils. A matched set of pen and pencil using the principles of the present invention is particularly contemplated.
Pens which have various forms of ornamentation thereon are known, for example, in U.S. Pat. No. 6,299,373 B1, which discloses a ring assembly for a pen wherein adhesion of a decorative sticker on the barrel of the pen is reinforced. U.S. Pat. No. 1,387,625 discloses interchangeable display exhibits, such as pictures or inscriptions, which are attachable to pencils or pen holders. U.S. Pat. No. 1,262,788 discloses advertising displays on split sleeve-like attachments which slide over the barrel of a pencil or pen. A more recent reference, U.S. Pat. No. 6,332,727 B1, discloses a whimsical ball point pen having ornamentation wherein an ornament body produces diverse shapes. Multiple direction changes cause the ornament to make amusing twisting dances with the rotation of the pen barrel.
Unlike the prior pens and pencils disclosed in these references, the present invention relates to ornamentations on writing instruments, both pens and pencils, which are of intricately designed pewter metal and which are cast thereon by a centrifugal casting technique. Centrifugal, or spin, casting has been employed in the past to make costume jewelry, ornamental items, and metal castings, and wax investment casting patterns for precision engineered products. Such casting methods offer economic advantages in low volume production and employ relatively low cost tooling.
Centrifugal casting generally involves use of a pair of complementary disk-shaped rubber mold halves which are formed with a series of cavities therein. When the complementary rubber mold halves are placed together, a multi-cavity mold is formed. This multi-cavity rubber mold is clamped together by air pressure between rotatable metal plates in a motor driven table. As the mold spins on the table, molten metal is poured into the center sprue of the mold, and the metal is forced outwardly through radial passageways in the mold by the centrifugal forces imposed by the spinning, and fills the mold cavities. Rotation speeds typically can range from 100 to 1000 RPM, depending on the size of the mold and the material being cast. When the mold charge is completed, the rotation may be stopped, the mold cooled and opened, and the cast parts removed.
By this technique, emblems to be cloisonned have been made, as discussed in U.S. Pat. No. 4,597,146, formed of aluminum, zinc, lead, tin or other alloys to produce pewter, electrotype lead, white metal or other alloy having a low melting temperature. U.S. Pat. No. 5,040,590 discloses apparatus said to be useful in cooling the molds employed in centrifugal casting of metals used in the production of costume jewelry.
Nowhere in the known art is a teaching or suggestion of highly detailed, pewter metal ornamentations cast on and affixed to writing instruments by a centrifugal casting technique. The production of such unique writing instruments is an objective of this invention.